There has conventionally been known a ball for ball games that has a ball body and an outer layer that is configured by stitching adjacent leather panels together and covers the ball body. This type of ball for ball games is disclosed in, for example, Patent Literature 1 and 2.
The ball for ball games disclosed in Patent Literature 1 has a ball body 57 consisting of a bladder 52 and a reinforcing layer 53, and an outer layer 55 disposed on the outside of the ball body 57, as shown in FIG. 14. The outer layer 55 has a plurality of leather panels 54. The leather panels 54 each have a leather 54c and a foam material 54d bonded to the rear surface of the leather 54c. A peripheral portion of each leather panel 54 has a folding portion 59, wherein the adjacent leather panels 54, 54 are stitched together with a stitching thread 63 at the folding portion 59.
In this ball for ball games, the foam material 54d is bonded to the rear surface of the leather 54c, and an outer end portion of the leather panel 54 is thinner than the center of the leather panel 54. Therefore, the peripheral portion of the leather panel 54 is not bulging, and the ball feels soft. Moreover, the leather panels 54 are bonded to each other, preventing water from seeping into the leather panels 54 from between the leather panels 54, 54.
However, stitching the foam materials 54d together at the folding portions 59 of the leather panels 54 generates weak sewing strength. As a result, seam tear and stitch-skipping are likely to occur at the time of sewing. In addition, because the strength of the foam materials 54d is extremely lower than that of the stitching thread 63, the foam material 54d and the leather 54c tear at the stitched portion when the ball is subjected to impact when kicked, resulting in a critical problem that the leather panels 54 come off.
In the ball for ball games disclosed as an embodiment in Patent Literature 2 as well, the peripheral portion of each leather panel 54 is not bulging due to the presence of a pad material 65 as shown in FIG. 15, and the ball feels soft. However, because the adjacent leather panels 54, 54 are not bonded to each other, the force that splits the adjacent panels 54, 54 apart acts on the stitched portion between the leather panels 54 when the ball for ball games is in use, possibly exposing the stitching thread 63. In addition, sewing strength is weak because the leathers 54c are stitched together. Consequently, seam tear and stitch-skipping are likely to occur. There is also a risk that this action of the force splitting the adjacent leather panels 54, 54 apart might tear the stitching thread 63. Furthermore, water is absorbed between the leather panels 54, 54.
The ball for ball games disclosed as an embodiment in Patent Literature 2 has a lining layer 67, as shown in FIG. 16. This lining layer 67 is stitched together with the leather 54c and an intermediate layer 69, providing high sewing strength. In this embodiment, however, the adjacent leather panels 54, 54 are not bonded to each other, and due to the absence of the pad material 65, the peripheral portion of each leather panel 54 bulges. As a result, when this ball for ball games is in use, the force that splits the adjacent panels 54, 54 apart acts more easily on the stitched portion of each leather panel 54, compared to the embodiment shown in FIG. 15. Consequently, the stitching thread 63 becomes exposed easily. In addition, there is a risk that this action of the force splitting the adjacent leather panels 54, 54 apart might tear the stitching thread 63.